On Friday, the Amazing Adaptations exhibit — a 60-foot, 3,000-gallon facility featuring seahorses, seadragons and pipefish — will open to the public.

The exhibit includes nine tanks showcasing a diverse collection of species, from local pipefish to exotic Australian seadragons.

“We’ve actually got some of the biggest species of seahorse in the world, which is the potbelly seahorse,” said aquarium director Andrew Rossiter. “They get about 12 inches in size, and we’ve got some of the smallest ones as well, the pigmy seahorse, and they reach about an inch in size. The ones we’ve got are about a half-inch. They’re very hard to see, but you can get up close and personal.”

It took six years to plan and complete, aquarium officials say.

Guests will be invited to participate in interactive educational activities between 9 a.m. and 1 p.m., and learn about the elusive marine creatures from Aquarium experts from around the world.

“One of the really interesting things about these fishes is it’s the male that either carry the eggs or takes care of the young,” Rossiter said. “The female does practically nothing and actually the seahorse is the only vertebrate animal — the only animal with a backbone — in which the male gets pregnant. Women love that one.”

Keiki will be encouraged to wear seahorse costumes to receive free admission, and the first 100 families through the door will receive a “seahorse pouch” with a seahorse charm, Hard Rock Cafe goodies and a seadragon book written and illustrated by local authors.